ASTM E1304-97

Standard Test Method for Plane-Strain (Chevron-Notch) Fracture Toughness of Metallic Materials

SCOPE
1.1 This test method covers the determination of plane-strain (chevron-notch) fracture toughnesses, KIv  or K IvM, of metallic materials. Fracture toughness by this method is relative to a slowly advancing steady state crack initiated at a chevron-shaped notch, and propagating in a chevron-shaped ligament (Fig. 1). Some metallic materials, when tested by this method, exhibit a sporadic crack growth in which the crack front remains nearly stationary until a critical load is reached. The crack then becomes unstable and suddenly advances at high speed to the next arrest point. For these materials, this test method covers the determination of the plane-strain fracture toughness,  KIvj  or KIvM, relative to the crack at the points of instability.
Note 1—One difference between this test method and Test Method E 399 (which measures K Ic) is that Test Method E 399 centers attention on the start of crack extension from a fatigue precrack. This test method makes use of either a steady state slowly propagating crack, or a crack at the initiation of a crack jump. Although both methods are based on the principles of linear elastic fracture mechanics, this difference, plus other differences in test procedure, may cause the values from this test method to be larger than KIc values in some materials. Therefore, toughness values determined by this test method cannot be used interchangeably with KIc.
1.2 This test method uses either chevron-notched rod specimens of circular cross section, or chevron-notched bar specimens of square or rectangular cross section (Figs. 1-10). The terms "short rod" and "short bar" are used commonly for these types of chevron-notched specimens.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Apr-1997
• Technical Committee: E08 - Fatigue and Fracture
• Drafting Committee: E08.02 - Terminology

Relations

• Replaced By: ASTM E1304-97(2002) - Standard Test Method for Plane-Strain (Chevron-Notch) Fracture Toughness of Metallic Materials
• Effective Date: 10-Apr-1997
• Referred By: ASTM F3122-14(2022) - Standard Guide for Evaluating Mechanical Properties of Metal Materials Made via Additive Manufacturing Processes
• Effective Date: 10-Apr-1997
• Referred By: ASTM B646-19 - Standard Practice for Fracture Toughness Testing of Aluminum Alloys
• Effective Date: 10-Apr-1997
• Referred By: ASTM E1221-12A(2018)e1 - Standard Test Method for Determining Plane-Strain Crack-Arrest Fracture Toughness, <emph type="bdit">K<inf>Ia</inf></emph>, of Ferritic Steels
• Effective Date: 10-Apr-1997
• Referred By: ASTM E1823-23 - Standard Terminology Relating to Fatigue and Fracture Testing
• Effective Date: 10-Apr-1997

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 1304 – 97
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Plane-Strain (Chevron-Notch) Fracture Toughness of
Metallic Materials
This standard is issued under the fixed designation E 1304; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of plane-
strain (chevron-notch) fracture toughnesses, K or K ,of
Iv IvM
metallic materials. Fracture toughness by this method is
relative to a slowly advancing steady state crack initiated at a
chevron-shaped notch, and propagating in a chevron-shaped
ligament (Fig. 1). Some metallic materials, when tested by this
method, exhibit a sporadic crack growth in which the crack
front remains nearly stationary until a critical load is reached.
The crack then becomes unstable and suddenly advances at
high speed to the next arrest point. For these materials, this test
method covers the determination of the plane-strain fracture
NOTE 1—The crack commences at the tip of the chevron-shaped
ligament and propagates (shaded area) along the ligament, and has the
toughness, K or K , relative to the crack at the points of
Ivj IvM
length “a” shown. (Not to scale.)
instability.
FIG. 1 Schematic Diagrams of Chevron-Notched Short Rod (a)
NOTE 1—One difference between this test method and Test Method and Short Bar (b) Specimens
E 399 (which measures K ) is that Test Method E 399 centers attention on
Ic
the start of crack extension from a fatigue precrack. This test method E 399 Test Method for Plane-Strain Fracture Toughness of
makes use of either a steady state slowly propagating crack, or a crack at
Metallic Materials
the initiation of a crack jump. Although both methods are based on the
E 1823 Terminology Relating to Fatique and Fracture Test-
principles of linear elastic fracture mechanics, this difference, plus other
ing
differences in test procedure, may cause the values from this test method
to be larger than K values in some materials. Therefore, toughness values
Ic
3. Terminology
determined by this test method cannot be used interchangeably with K .
Ic
3.1 Definitions:
1.2 This test method uses either chevron-notched rod speci-
3.1.1 The terms described in Terminology E 1823 are ap-
mens of circular cross section, or chevron-notched bar speci-
plicable to this test method.
mens of square or rectangular cross section (Figs. 1-10). The −3/2
3.1.2 stress-intensity factor, K (dimensional units FL )—
I
terms “short rod” and “short bar” are used commonly for these
the magnitude of the ideal crack-tip stress field singularity for
types of chevron-notched specimens.
mode I in a homogeneous linear-elastic body.
1.3 This standard does not purport to address all of the
3.1.2.1 Discussion—Values of K for mode I are given by:
safety concerns, if any, associated with its use. It is the
½
K 5 limit s 2pr
@ #
responsibility of the user of this standard to establish appro- I y x
priate safety and health practices and determine the applica-
r →0
x
bility of regulatory limitations prior to use.
where:
2. Referenced Documents r 5 a distance directly forward from the crack tip to a
x
location where the significant stress is calculated and
2.1 ASTM Standards:
s 5 the principal stress r normal to the crack plane.
y x
E 4 Practice for Force Verification of Testing Machines
2 3.2 Definitions of Terms Specific to This Standard:
E 8 Test Methods for Tension Testing of Metallic Materials
3.2.1 plane-strain (chevron-notch) fracture toughness, K
Iv
−3/2
or K (FL )—under conditions of crack-tip plane strain in a
Ivj
This test method is under the jurisdiction of ASTM Committee E-8 on Fracture chevron-notched specimen: K relates to extension resistance
Iv
Fatigue and is the direct responsibility of Subcommittee E08.07 on Fracture
with respect to a slowly advancing steady-state crack. K
Ivj
Linear–Elastic.
relates to crack extension resistance with respect to a crack
Current edition approved Apr. 10, 1997. Published June 1997. Originally
which advances sporadically.
published as E 1304 – 89. Last previous edition E 1304 – 89.
Annual Book of ASTM Standards, Vol 03.01. 3.2.1.1 Discussion—For slow rates of loading the fracture
E 1304
NOTE 1—See Table 1 for tolerances and other details.
FIG. 2 Rod Specimens Standard Proportions
NOTE 1—See Table 2 for tolerances and other details.
FIG. 3 Bar Specimens Standard Proportions
toughness, K or K , is the value of stress-intensity factor as 3.2.4 crack jump behavior—in tests of chevron-notch speci-
Iv Ivj
measured using the operational procedure (and satisfying all of mens, that type of sporadic crack growth which is character-
the validity requirements) specified in this test method. ized primarily by periods during which the crack front is nearly
3.2.2 plane-strain (chevron-notch) fracture toughness, K stationary until a critical force is reached, whereupon the crack
IvM
−3/2
(FL )—determined similarly to K or K (see 3.2.1) using becomes unstable and suddenly advances at high speed to the
Iv Ivj
the same specimen, or specimen geometries, but using a next arrest point, where it remains nearly stationary until the
simpler analysis based on the maximum test force. The force again reaches a critical value, etc. (see Fig. 5).
analysis is described in Annex A1. Unloading-reloading cycles 3.2.4.1 Discussion—A chevron-notch specimen is said to
as described in 3.2.6 are not required in a test to determine have a crack jump behavior when crack jumps account for
K . more than one half of the change in unloading slope ratio (see
IvM
3.2.3 smooth crack growth behavior—generally, that type of 3.2.6) as the unloading slope ratio passes through the range
crack extension behavior in chevron-notch specimens that is from 0.8r to 1.2r (see 3.2.6 and 3.2.7, and 8.3.5.2). Only
c c
characterized primarily by slow, continuously advancing crack those sudden crack advances that result in more than a 5 %
growth, and a relatively smooth force displacement record decrease in force during the advance are counted as crack
(Fig. 4). However, any test behavior not satisfying the condi- jumps (Fig. 5).
tions for crack jump behavior is automatically characterized as 3.2.5 steady-state crack—a crack that has advanced slowly
smooth crack growth behavior. until the crack-tip plastic zone size and crack-tip sharpness no
E 1304
R # 0.010B
f # 60°
s
t # 0.03B
NOTE 1—These requirements are satisfied by slots with a round bottom
whenever t # 0.020B.
FIG. 6 Slot Bottom Configuration
FIG. 4 Schematic of a Load-Displacement Test Record for
Smooth Crack Growth Behavior, with Unloading/Reloading
Cycles, Data Reduction Constructions, and Definitions of Terms
FIG. 5 Schematic of a Load-Displacement Test Record for Crack
Jump Behavior, with Unloading/Reloading Cycles, Data
Reduction Constructions, and Definitions of Terms
NOTE 1—Machine finish all over equal to or better than 64 μin.
NOTE 2—Unless otherwise specified, dimensions 60.010B; angles
62°.
longer change with further crack extension. Although crack-tip
NOTE 3—Grip hardness should be RC 5 45 or greater.
conditions can be a function of crack velocity, the steady-state
FIG. 7 Suggested Loading Grip Design
crack-tip conditions for metals have appeared to be indepen-
dent of the crack velocity within the range attained by the
is measured by performing unloading-reloading cycles during
loading rates specified in this test method.
the test as indicated schematically in Fig. 4 and Fig. 5. For each
3.2.6 effective unloading slope ratio, r—the ratio of an
unloading-reloading trace, the effective unloading slope ratio,
effective unloading slope to that of the initial elastic loading
r, is defined in terms of the tangents of two angles:
slope on a test record of force versus specimen mouth opening
displacement.
r 5 tan u/tan u
o
3.2.6.1 Discussion—This unloading slope ratio provides a
where:
method of determining the crack length at various points on the
tan u 5 the slope of the initial elastic line, and
o
test record and therefore allows evaluation of stress intensity
tanu5 the slope of an effective unloading line.
coefficient Y* (see 3.2.11). The effective unloading slope ratio
E 1304
FIG. 9 Suggested Design for the Specimen Mouth Opening Gage
NOTE 1—To assist alignment, shims may be placed at these locations
and removed before the load is applied, as described in 8.3.2.
FIG. 8 Recommended Tensile Test Machine Test Configuration
The effective unloading line is defined as having an origin at
the high point where the displacement reverses direction on
unloading (slot mouth begins to close) and joining the low
NOTE 1—Compiled from Refs (8), (10), (11), and (13).
point on the reloading line where the force is one half that at
FIG. 10 Normalized Stress-Intensity Factor Coefficients as a
the high point.
Function of Slope Ratio (r) for Chevron-Notch Specimens
3.2.6.2 Discussion—For a brittle material with linear elastic
behavior the unloading-reloading lines of an unloading-
3.2.8 critical crack length—the crack length in a chevron-
reloading cycle would be linear and coincident. For many
notch specimen at which the specimen’s stress-intensity factor
engineering materials, deviations from linear elastic behavior
coefficient, Y* (see 3.2.11 and Table 3), is a minimum, or
and hysteresis are commonly observed to a varying degree.
equivalently, the crack length at which the maximum force
These effects require an unambiguous method of obtaining an
would occur in a purely linear elastic fracture mechanics test.
effective unloading slope from the test record (1-4).
At the critical crack length, the width of the crack front is
3.2.6.3 Discussion—Although r is measured only at those
approximately one third the dimension B (Figs. 2 and 3).
crack positions where unloading-reloading cycles are per-
3.2.9 high point, High—the point on a force-displacement
formed, r is nevertheless defined at all points during a
plot, at the start of an unloading-reloading cycle, at which the
chevron-notch specimen test. For any particular point it is the
displacement reverses direction, that is, the point at which the
value that would be measured for r if an unloading-reloading
specimen mouth begins closing due to unloading (see points
cycle were performed at that point.
labeled High in Figs. 4 and 5).
3.2.7 critical slope ratio, r —the unloading slope ratio at
3.2.10 low point, Low—the point on the reloading portion of
c
the critical crack length.
an unloading-reloading cycle where the force is one half the
high point force (see points labeled Low in Figs. 4 and 5).
3.2.11 stress-intensity factor coeffıcient, Y*—a dimension-
The boldface numbers in parentheses refer to the list of references at the end
of this standard. less parameter that relates the applied force and specimen
E 1304
TABLE 1 Rod Dimensions TABLE 2 Bar Dimensions
NOTE 1—All surfaces to be 64-μin. finish or better. NOTE 1—All surfaces to be 64-μin. finish or better.
NOTE 2—Side grooves may be made with a plunge cut with a circular NOTE 2—Side grooves may be made with a plunge cut with a circular
blade, such that the sides of the chevron ligament have curved profiles, blade, such that the sides of the chevron ligament have curved profiles,
provided that the blade diameter exceeds 5.0B. In this case, f is the angle provided that the blade diameter exceeds 5.0B. In this case, f is the angle
between the chords spanning the plunge cut arcs, and it is necessary to use between the chords spanning the plunge cut arcs, and it is necessary to use
different values of f and a (4), so that the crack front has the same width different values of f and a (4), so that the crack front has the same width
o o
as with straight cuts, at the critical crack length. as with straight cuts, at the critical crack length.
NOTE 3—The dimension a must be achieved when forming the side NOTE 3—The dimension a must be achieved when forming the side
o o
grooves. A separate cut that blunts the apex of the chevron ligament is not grooves. A separate cut that blunts the apex of the chevron ligament is not
permissible. permissible.
NOTE 4—Grip groove surfaces are to be flat and parallel to chevron NOTE 4—Grip groove surfaces are to be flat and parallel to chevron
notch within6 2°. notch within6 2°.
NOTE 5—Notch on centerline within 60.005B and perpendicular or NOTE 5—Notch on centerline within 60.005B and perpendicular or
parallel to surfaces as applicable within 0.005B (TIR). parallel to surfaces as applicable within 0.005B (TIR).
NOTE 6—The imaginary line joining the conical gage seats must be NOTE 6—The imaginary line joining the conical gage seats must be
perpendicular (62°) to the plane of the specimen slot. perpendicular (62°) to the plane of the specimen slot.
Value Value
Sym- Sym-
Name Tolerance Name Tolerance
bol bol
W/B 5 1.45 W/B 5 2.0 W/B 5 1.45 W/B 5 2.0
B Diameter BB . B Thickness BB .
W Length 1.450B 2.000B 60.010B W Length 1.450B 2.000B 60.010B
a Distance to chevron tip 0.481B 0.400B 60.005B a Distance to chevron tip 0.481B 0.400B 60.005B
o o
S Grip groove depth 0.150B 0.150B 60.010B S Grip groove depth 0.150B 0.150B 60.010B
alternate groove 0.130B 0.130B 60.010B alternate groove 0.130B 0.130B 60.010B
X Distance to load line 0.100B 0.100B 60.003B X Distance to load line 0.100B 0.100B 60.003B
alternate groove 0.050B 0.050B 60.003B alternate groove 0.050B 0.050B 60.003B
T Grip groove width 0.350B 0.350B 60.005B T Grip groove width 0.350B 0.350B 60.005B
alternate groove 0.313B 0.313B 60.005B alternate groove 0.313B 0.313B 60.005B
A A A A
t Slot thickness #0.030B #0.030B . t Slot thickness #0.030B #0.030B .
f Slot angle 54.6° 34.7° 60.5° f Slot angle 54.6° 34.7° 60.5°
H Half-height
A
See Fig. 6.
(square specimen) 0.500B 0.500B 60.005B
B
(rectangular spec- 0.435B 60.005B
imen)
geometry to the resulting crack-tip stress-intensity factor in a
A
See Fig. 6.
chevron-notch specimen test (see 9.6.3). B
See Note 1.
3.2.11.1 Discussion—Values of Y* can be found from the
graphs in Fig. 10, or from the tabulations in Table 4 or from the
TABLE 3 Minimum Stress-Intensity Factor Coefficients and
polynominal expressions in Table 5. Critical Slope Ratios for Chevron-Notch Specimens
3.2.12 minimum stress-intensity factor coeffıcient, Y*
m
NOTE 1—The v
...